Adjuvant therapies are additional treatments, such as chemotherapy or radiation therapy, that help kill remaining cancer cells after primary therapy, like surgery, is complete.

Treating breast cancer often requires an approach from several fronts. While surgery to remove a tumor can be effective, sometimes your doctor may also recommend adjuvant therapy to increase the chances of removing all cancerous cells throughout your body.

Adjuvant therapies are treatments that follow your main treatment. They’re used to eliminate any remaining cancer cancer cells and to reduce the chance of your cancer coming back.

This article reviews the goals of adjuvant therapies and what types of adjuvant therapies may be used for breast cancer.

Adjuvant therapies are additional treatments that help kill any cancer cells remaining in the body after a primary therapy like surgery.

Types of adjuvant therapies that may be used for breast cancer include:

In some cases, your doctor may recommend neoadjuvant therapy. This is a type of therapy that’s given before the main treatment.

This form of therapy can make the primary treatment more effective. For example, if your primary treatment is surgery to remove a tumor, neoadjuvant therapy can help shrink the tumor and improve the success rate of the surgery.

There are different types of adjuvant therapy for breast cancer. Your doctor may recommend one or more of the following at any time during your cancer treatment.


Adjuvant chemotherapy involves using anticancer drugs to kill any remaining cancer cells after surgery.

Because these cells are often difficult to see, even on imaging tests, your doctor may recommend adjuvant chemotherapy to lower the risk of breast cancer returning after surgery, according to the American Cancer Society.

When used before surgery (neoadjuvant), the goal is to shrink the tumor, so the removal is easier and requires less extensive surgery.

Chemotherapy drugs used for adjuvant therapy include:

Radiation therapy

Adjuvant radiation therapy helps target cancer cells by using high doses of radiation to kill cancer cells that remain in the breast or lymph nodes after surgery, per the National Cancer Institute.

There are two types of radiation: external beam radiation and internal radiation (brachytherapy).

With external radiation, a machine outside your body aims radiation at cancer cells. Internal radiation places radiation inside your body in or near the cancer.

According to the National Cancer Institute, external beam radiation is the most common type used for breast cancer treatment.

However, your doctor will likely wait until the surgery site is healed before starting external beam radiation as adjuvant therapy.

Hormone therapy

Hormone therapy uses certain medications to stop hormone production in the body or to alter how they affect the body. According to the American Cancer Society, this type of adjuvant therapy is recommended for hormone receptor-positive tumors. Treatment with hormone therapy typically lasts about 5 years.

The drugs used for hormone therapy either stop estrogen from helping cells grow or lower estrogen levels in the body.

Drugs that block estrogen receptors include tamoxifen, toremifene, and fulvestrant. Drugs that lower estrogen levels include aromatase inhibitors.

Tamoxifen is appropriate for pre- and postmenopausal people, while toremifene is only approved to treat postmenopausal patients with metastatic breast cancer.

Fulvestrant is also recommended for postmenopausal people with locally advanced breast cancer and metastatic breast cancer.

Aromatase inhibitors (AIs) are better suited for postmenopausal people or premenopausal people with suppressed ovaries. AIs include letrozole, anastrozole, and exemestane.


Immunotherapy is a type of biological therapy sometimes used during breast cancer treatment. According to the American Cancer Society, immunotherapy involves the use of medication to boost your immune system so it can recognize and destroy cancer cells more effectively.

Immune checkpoint inhibitors are the most common type of immunotherapy.

Currently, there are two immune checkpoint inhibitors approved by the FDA for metastatic triple-negative breast cancer and high risk early stage triple-negative breast cancer, respectively: atezolizumab and pembrolizumab.

Targeted therapy

Your doctor may suggest a targeted therapy to focus on specific abnormalities in the cancer cells.

In addition to identifying and destroying cancer cells while leaving other cells undamaged, these drugs also detect and block messages inside the cell that tell it to grow, according to the American Cancer Society.

HER2-positive breast cancer is one type of cancer that can respond to targeted therapies like monoclonal antibodies, antibody-drug conjugates, and kinase inhibitors.

In general, breast cancer responds well to adjuvant therapy. However, treatment for breast cancer should be individuated and designed to meet your unique needs. That’s why certain treatments, like adjuvant therapy, are better suited for some people.

More specifically, people with a high risk of cancer returning are good candidates for adjuvant therapy. This includes people in later stages of cancer or with cancer that has spread to nearby lymph nodes.

Your doctor will also discuss the side effects of each adjuvant therapy with you so you can decide if the benefits outweigh the risks.

Overall, breast cancer responds well to adjuvant therapy. However, there are some risks to consider before moving forward.

Side effects are generally specific to the type of treatment, dose, and your general health.

Chemotherapy side effects may include:

  • hair loss
  • appetite changes
  • nausea and vomiting
  • fatigue
  • hot flashes
  • mouth sores
  • nail changes
  • diarrhea
  • changes in menstrual periods in younger patients
  • nerve damage (rare)

Radiation side effects may include:

  • skin changes in the treated area
  • hair loss
  • fatigue
  • breast swelling
  • breast pain
  • infection, redness, or bruising at the treatment site for brachytherapy

Hormone therapy side effects may include:

  • hot flashes (all hormone therapy drugs)
  • menstrual cycle changes (tamoxifen and toremifene)
  • vaginal dryness (aromatase inhibitors, tamoxifen, and toremifene)
  • bone issues (tamoxifen)
  • headache (fulvestrant)
  • mild nausea (fulvestrant)
  • bone pain (fulvestrant and aromatase inhibitors)
  • injection site pain (fulvestrant)

Immunotherapy side effects may include:

  • fatigue
  • cough
  • skin rash
  • nausea
  • changes in appetite
  • diarrhea
  • constipation
  • infusion reaction, which is similar to an allergic reaction

Targeted therapy side effects depend on the therapy and are often mild. More serious side effects may include:

  • severe diarrhea
  • liver problems
  • lung problems
  • heart issues
  • hand-foot syndrome

What is the difference between adjuvant therapy and chemotherapy?

Adjuvant therapy is a type of treatment that’s given after primary therapy, like surgery, is complete. It’s used to kill any remaining cancer cells. Types of adjuvant therapy include chemotherapy, radiation therapy, hormone therapy, and immunotherapy.

What is the meaning of adjunct therapy?

Adjunct therapy is a treatment that’s used alongside primary treatment, rather than before or after. Types of adjunct therapy include chemotherapy, hormone therapy, radiation therapy, targeted therapy, or immunotherapy.

What does adjuvant mean in medical terms?

An adjuvant is an ingredient that’s added to some vaccines. They’re used to increase a person’s immune response to the disease the vaccine is being used for.

Vaccines with adjuvants may produce more local reactions at the injection site, such as redness or swelling, and more systemic reactions, such as fever, chills, and body aches

Why can’t you share a bathroom with someone on chemo?

It can take approximately 48—72 hours for your body to break down and eliminate most chemotherapy drugs. Some drugs may take longer.

Most of the drug waste is removed from your body via urine, tears, sweat, and vomit. Depending on the drug used, it may also be found in other body fluids, such as in semen or discharge from the vagina.

Other people and pets you may live with can be exposed to drug waste if they come into contact with any of your body fluids. For this reason, if you’re undergoing chemotherapy, it’s a good idea to:

  • have children use a different toilet than the one you use
  • flush the toilet twice after using it (and put the lid down before flushing to avoid splashing)
  • keep the toilet lid down when not using so pets can’t drink from the water
  • wash your hands with soap and warm water after using the toilet, and dry your hands with paper towels (rather than shared towels) and throw them away after using.

Adjuvant therapies are additional treatments that help address any cancer remaining in the body after a primary therapy like surgery. Sometimes these therapies may be used before another therapy. In this case, they’re referred to as neoadjuvant therapies.

While adjuvant therapy does not guarantee that cancer won’t recur, it can reduce the risk of it returning.

Examples of adjuvant therapy for breast cancer include chemotherapy, radiation, hormone therapy, immunotherapy, and targeted therapies. The type of breast cancer and stage, along with other factors, will determine the adjuvant therapy that will work best for you.

It’s important to talk with your doctor about your treatment options. They can answer any questions you may have about adjuvant therapy and help you decide the best treatment for you.